FULL RANGE FEEDWATER CONTROL SYSTEM FOR PRESSURIZED WATER REACTOR STEAM GENERATORS

摘要

PURPOSE: A full range feedwater control system for pressurized water reactor steam generators is provided to simplify the FWCS design, to make the system more reliable, and to reduce its capital operating cost by using a feedwater control system which has three input signal for determining a processing step and one of them determines the next processing with reference to a certain power level. CONSTITUTION: A feedwater control system for a pressurized water steam generating system, and a method for using such, includes a steam generator, at least one feedwater pump which receives an output signal from the feedwater control system, an economizer feedwater control valve which receives the output signal and automatically controls flow of feedwater to the steam generator when a power level of the feedwater control system is at a first predetermined range, preferably between about 10 and 100%, and a downcomer feedwater control valve which receives the output signal and automatically controls the flow of feedwater to the steam generator when the power level is at a second predetermined range, preferably between 0 and about 10%. A first input signal is provided, determined by the feedwater flow of the steam generator, along with a second input signal, determined by the steam flow of the steam generator, and a third input signal, determined by the level of the steam generator. The first, second, and third input signals are combined to determine the output signal at the first predetermined power level range, and the third input signal, by itself, determines the output signal at the second predetermined power level range. A switch automatically switches from the combined first, second, and third input signals, to just the third input signal, for determining the output signal, at a predetermined power level, i.e. at about 10% power.